Hi
I want to make voltmeter using an arduino uno.
after searching I found that I need 10K and 100K resistors.
is it possible to use 10K instead of 100K ? (I mean only two 10K resistors for voltmeter)
thanks
Hi
I want to make voltmeter using an arduino uno.
after searching I found that I need 10K and 100K resistors.
is it possible to use 10K instead of 100K ? (I mean only two 10K resistors for voltmeter)
thanks
What kind of voltages do you want to measure ?
If that voltage is higher than 5V, then you need a voltage divider with two resistors.
The value of those resistors depend on what you want.
When the Arduino reads a voltage with an analog pin, the reference is by default the 5V. If, for example, your Arduino board is powered by the USB cable, that voltage can vary a lot. That will make the voltages that you measure inaccurate.
Using the internal voltage reference of 1.1V is better.
Using an external voltage reference with a very good overall accuracy is even better.
Is there a tutorial that you use ? Can you give a link to it ?
currently I'm using 9v battery, but after that I need to be able to get the LiPo battery voltage.
I would be appreciate if you can help me with both of these scenarios.
tuts:
http://fritzing.org/projects/arduino-voltmeter
Arduino Project Hub (in the code sections resistors are 10K & 100K)
thanks
You can use 10k and 10k to measure a 9V battery. Because two 10k resistors will divide the voltage in half. The Arduino will get 4.5V at the analog pin.
But don't expect it to be accurate.
There will be current through the resistors. That leakage current can be lowered when 100k and 10k are used.
The tutorial in the first link is confusing. There is a link and then I get lost. Is one of the 50 tutorials a battery voltage meter ?
The second tutorial is better.
When a analog pin is used, there is no need to set that pin as a digital pin (as is done in the second tutorial). I also prefer to use 'A1' instead of '1' for an analog pin.
I don't know the voltage of the LiPo cell or pack.
thanks for your great responses.
they helped me alot.
"The lipo battery" tells us not a lot. If it's a 1S (3.7V nominal) or 2s (7.4V nominal) lipo it will be fine.
If it's a 3S (11.1V nominal, 12.6V maximum) or higher it definitely won't.
Basically with a voltage divider made of 2 identical resistors you're safe to 10V input, not higher.
Steve